Plasticized polyvinyl chloride compound

ABSTRACT

A highly flame retardant plasticized polyvinyl chloride compound (PVC) comprises a mixture of dialkyl tetrachlorophthalate and dialkyl tetrabromophthalate and is characterized by an absence of brittleness, and substantial flexibility at low temperatures as required for PVC formed jackets and insulation for wire and cable products.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a highly flame retardant plasticizedpolyvinyl chloride compound (PVC) further characterized by an absence ofbrittleness at low temperatures, and substantial flexibility such asrequired for PVC formed jackets and insulation for wire and cableproducts and sheets often used, for example, as roof sheathing uponwhich shingles or other roof covering is laid.

[0003] 2. Description of the Related Art

[0004] PVC compounds (PVC) are a well known class of thermoplasticpolymers which exhibit excellent chemical and corrosion resistance,physical and mechanical strength, and electrical insulative properties.Unplasticized versions of PVC are inherently flame resistant and rigidPVC compounds require only additional antimony trioxide to achieve ahigh level of flame retardancy. However, when flexible forms of PVC arerequired, the addition of plasticizers result in increased flammabilityof PVC. Conventional PVC is also apt to produce excessive smoke whenignited.

[0005] Both triaryl and diaryl alkyl phosphate esters have been used toimprove the flame retardancy of PVC. High flame retardant demands formore stringent flexible PVC applications, such as outer jackets andinsulators for plenum wires and cables, for sheets used in theconstruction industry, for example, as roof sheathing upon whichshingles or other roof coverings are laid, as well as for flexiblecoatings applied to fabrics, have required improvements in the flameretardant plasticizers incorporated in these compounds. The additionalof dialkyl tetrahalophthalates such as dioctyl tetrabromophthalate ordi-2-ethylhexyltetrabromophthalate have been able to achieve exceptionalthermal stability with exceptional flame retardancy. However, the lowtemperature flexibility of PVC compounds is compromised with theaddition of such compounds.

[0006] It is known that flame retardant synergy is exhibited by certainbrominated and chlorinated compounds. (By use of the term “flameretardant synergy” it is meant that the action of two or more substancesachieve an effect of which each is individually incapable.) For example,a paper entitled Bromine-Chlorine Synergy To Flame Retard ABS Resins, bySeunghee Yun and Hyunkoo Kim of Miwon Petrochemical Corporation,presented at the New Developments and Future Trends in Fire Safety On AGlobal Basis International Conference, March 1997, discusses mixtures ofDECHLORANE™ PLUS, a product of Occidental Chemical Corporation, and TBBA(Tetrabromobisphenol A), or FF-680 (Bis(Tribromophenoxy)Ethane) toproduce acrylonitrile butadiene styrene (ABS) resins having improvedflame retardant characteristics. However, the Yun and Kim results referto ABS, a rigid plastic used in electrical component housings (e.g. TVcabinets and computer casings). Yun and Kim use the chlorinatedsubstance Dechlorane Plus to increase the rigidity of the resultant ABS.Such rigidity would be a serious flaw in PVC formed jackets andinsulation for wire and cable products. Improvement of flame retardantproperties, as well as improvement of low temperature flexibility anddecreased smoke generation, has not heretofore been known when the typeof brominated and chlorinated compounds of the present invention areused in PVC compounds. The principal object of the present invention,therefore, is to provide a highly flame retardant plasticized PVC basedon the discovery that improved low temperature flexibility can beachieved by adding to PVC dialkyl tetrahalophthalate mixtures of thetype hereafter described.

[0007] Dialkyl tetrahalophthalates are produced from the reaction oftetrachlorophthalic acid or anhydride and/or tetrabromophthalic acid oranhydride with C₁-C₁₈ alkanols. The production of dialkyltetrabromophthalate and dialkyl tetrachlorophthalates is well known inthe field. Numerous processes have been described for the preparation ofdialkyl phthalates by esterification of various alcohols with phthalicanhydride or acid in the presence of acidic catalysts, such as sulfuricacid, phosphoric acid, toluene sulfonic acid, and methane sulfonic acid.For example, Spatz et al. (I & EC Product Res. and Dev. 8: 391, 1969)discloses the preparation of di-2-ethylhexyl tetrabromophthalate usingphosphoric acid catalysis. Nomura et al. (published Japanese PatentApplication No. 50-05701, 1975) describes the use of tetraalkyltitanates in the presence of alkali metal salt to prepare dialkyltetrabromophthalates. Sagara et al. (U.S. Pat. No. 4,284,793) disclosesa method for producing plasticizers with low residual titanium, in whichphthalic anhydride is reacted with an alcohol in the presence of atitanate catalyst. The resultant ester is treated with a solid alkali,such as sodium carbonate, and adsorbing agent(s) in the absence ofwater. Watanable et al. (U.S. Pat. No. 4,304,925) discloses a processfor purifying esters, such as those formed from phthalic anhydride andethyl hexyl alcohol, when organotitanium compounds are used ascatalysts, where water is added to the esterification mixture and themixture is heated. Mamnuzic et al. (U.S. Pat. No. 4,754,053) disclosesthe preparation of tetrabromophthalate diesters using sodium carbonatedecahydrate as an essential part of the process. Bohen et al. (U.S. Pat.Nos. 5,049,697 and 5,208,366) disclosed a process for the preparation ofdialkyl esters of polyhaloaromatic acids catalyzed by the use of variousorganometallic catalysts, such as organotitanates, as well asorgano-tin, antimony and zirconium compounds. However, these patents donot disclose nor suggest mixing tetrabromophthalate andtetrachlorophthalate for the purpose of improving low temperatureflexibility of PVC.

[0008] Accordingly, the primary object of this invention is to improvethe low temperature flexibility of highly flame retardant plasticizedPVC compounds by incorporating into PVC, according to the discovery ofthe invention, dialkyl tetrahalophthalate mixtures containing bothtetrabromophthalates and tetrachlorophthalates.

[0009] A further object of this invention is to decrease the smokegeneration character of PVC.

[0010] Another object is to provide an improved PVC approved for use inproducts such as insulation, jackets, coatings, and sheeting.

[0011] Other objects and advantages will be more fully apparent from thefollowing disclosure and claims.

SUMMARY OF THE INVENTION

[0012] The subject of this invention is to improve the low temperatureflexibility of highly flame retardant plasticized PVC compounds byincorporating into PVC dialkyl tetrahalophthalate mixtures containingboth tetrabromophthalates and tetrachlorophthalates. PVC containingtetrabromophthalate and tetrachlorophthalate mixtures show significantimprovements in their low temperature flexibility. PVC compounds of thepresent invention also result in synergist improvements of flameretardancy with decreased smoke generation.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

[0013] The principal object of this invention as previously stated is toimprove the low temperature flexibility of highly flame retardantplasticized PVC by the addition of dialkyl tetrahalophthalate mixtures.Preferably the dialkyl tetrahalophthalates used in the PVC compound ofthe present invention are prepared in accordance with the teachings ofthe separately filed co-pending patent application Ser. No. 08/554,262,which disclosed a new method for preparing nearly colorless, highlypure, tetrahalophthalates with an extremely low acid number. However, itis recognized that the dialkyl tetrahalophthalates used in the PVCcompound of the present invention may be prepared using methods alreadyknown in the art. When tetrahalophthalate compounds are made accordingto the method described in the '262 application, certain improvedcharacteristics of PVC useful to the present inventions are achieved.The method for preparing dialkyl tetrahalophthalates as taught by the'262 application is utilized by the present invention to produce thebrominated and chlorinated compounds which are incorporated into the PVCof the present invention resulting in an improved low temperatureflexibility characteristic. This method of the '262 application isdescribed next.

I. PREPARATION OF DIALKYL TETRAHALOPHTHALATES

[0014] The preferred method as taught in the '262 application forpreparing dialkyl tetrahalophthalates used in the present inventionutilizes a tetrahalophthalic compound selected from the group consistingof tetrahalophthalic anhydrides and tetrahalophthalic acids. Thetetrahalophthalic anhydride or acid used may be of tetrabromo- ortetrachloro- substitution on the aromatic ring, with tetrabromophthalicanhydride the preferred embodiment. The tetrahalophthalic compound isreacted with an excess of alkanol, as is known in the art, to form areaction mass. The alkanol is selected from C₁-C₁₈ alkanols, or amixture thereof The alkanol may be a C₁-C₁₈ primary or secondary alkanolwith linear or branched alkyl moieties. The preferred alkanols are2-ethylhexanol and 3,3,5-trimetltylhexanol, as well as mixtures ofC₈-C₁₅ alkanols resultant from Oxo- and Ziegler manufacturing processesas known in the art (see Weissermel, K. and Arpe, H-J., IndustrialOrganic Chemistry, pages 132-134, 206-208, VCH Publishers, New York,1978).

[0015] The tetrahalophthalic anhydride may contain up to 0.30% residualsulfuric acid. Residual sulfuric acid resultant from the preparation ofthe original tetrahalophthalic anhydride is removed by serial hot waterwashing or preferably by the neutralization with a first Group II alkalimetal salt, more preferably a Group II alkali metal salt of a lowercarbon chain acid, and most preferably magnesium or calcium acetate.This treatment must be done before esterification to achieve low productcolor. Lower carbon chain acids of the type identified herein are carbonchains containing approximately four or less carbons. If hot water isused (about 90° C.), typically 3-4, 300-ml aliquots of water (usuallyabout 1 part water to 2 parts anhydride+alkanol) have been found to besufficient to remove the residual sulfuric acid in the aqueous phase toless than 0.1%, when a mole of anhydride is using in the startingreaction mix. If less water is used, more washes are generally requiredto achieve the results of the invention. The water wash treatment, whilebeing effective, is substantially more time-consuming than adding aGroup II alkali metal salt, which is the preferred treatment.

[0016] Preferably, treatment first with a Group II alkali metal salt(first Group II alkali metal salt) is used instead of a water wash toremove acidity. A weak base is preferred, such as magnesium acetate, toneutralize the acid. Alternatively, calcium acetate may be used. Use ofan acetate ensures that the pH will be less than 7.0 which is criticalbecause the titanium catalyst is sensitive to, and is destroyed by,alkaline pH. The first Group II alkali metal salt is used at 0.01 to 10percent of the weight of the reaction mass (defined as the weight of theoriginal reactants, preferably at 0.1 to 0.5 weight percent, mostpreferably at stoichiometric levels equal to that of the residualsulfuric acid in the tetrahalophthalic anhydride.

[0017] The solution which has been water washed or treated with a firstGroup II alkali metal salt is dried by azeotroping out the water to acontent of less than 0.05% by means known in the art. The product isthen esterified with a neutral catalyst which may be an alkyl titanatecatalyst or zirconium tetrabutoxide. An alkyl titanate catalyst isnormally used in the industry. The esterification catalyst is a C₁-C₁₈tetraalkyl titanate, preferably a C₈-C₁₈ tetraalkyl titanate, which mostpreferably is an alkyl identical to that of the alkanol esterified intothe product, thereby limiting the preparation of mixed esters due to thetransesterification of the alkyl groups of the catalyst into theproduct.

[0018] The esterification is carried out in an inert atmosphere, such asargon or nitrogen, at 160-240° C., preferably at 190-210° C. Anazeotropic solvent or entrainer, such as a non-reactive aromatic oraliphatic hydrocarbon, for example, xylene or toluene as is known in theart, is added to shorten the esterification time. An inert carrier gas,such as argon, nitrogen, or carbon dioxide, may be used to drive off thereaction water formed during the esterification. The esterification iscontinued until residual acidity drops to less than 1.0 meq/100 gramsample, preferably less than 0.5 meq/100 gram sample at which time theexcess alkanol is removed by vacuum distillation. This vacuumdistillation decreases the residual acidity to less than 0.2 meq/100gram sample. Excess alcohol must be removed to increase flash point anddecrease volatility of the finished product.

[0019] In another important step, the residual acidity from the reactionis removed by the addition of 0.1 to 20 percent of a second Group IIalkali metal salt, such as magnesium silicate (Magnesol® from the DallasGroup) or calcium silicate, plus an equal weight of water. This step isdone after esterification; otherwise, the tetrahalo anhydride would beunnecessarily treated, which would consume raw material needlessly.Magnesium silicate makes the salts of titanium insoluble so that more ofthe turbidity-causing titanium drops out of the solution. Althoughmagnesium or calcium oxide, or magnesium or calcium hydroxide, may beused at an equal weight percent basis as the magnesium silicate, thereis a resultant decrease in filtration rates. Use of Group I alkalis,other than lithium hydroxide and lithium silicate is not desirablebecause of their alkalinity (loss of product yield with poorfiltration), and some metal contamination (Lithium and titanium) occurswith the lithium alkalis.

[0020] The addition of the water in the step discussed above isessential for the neutralization of the residual acidity by themagnesium silicate. Further, the water neutralizes the residualunreacted monoester intermediate. Water acts as a phase transfer agent.Magnesium silicate is a powder. The reaction conditions are 50-95° C.,preferably 90° C. for 1 to 4 hours after which the water of theneutralization is removed by vacuum distillation at 90-140° C. Thisdrying technique is essential to driving the neutralization tocompletion as well as the formation of a granular precipitant which iseasily removed with conventional filtration methods, such as vacuum orpressure filtration. The final product of the invention can be washedagain with lithium hydroxide if it is desired to increase the productpurity and assure the minimum level of acidity.

[0021] The treatment with magnesium silicate decreases product color 1to 5 Gardner color units (A.O.C.S. Method Td 12-64T) as compared to 5-15Gardner color units. This treatment essentially removes all residualtitanium, thus producing a haze-free product even at low temperatures.These Group II alkali metal silicates are particular advantageous sincefilter aids, such as diatomaceous earth, are not required and the GroupII alkali metal silicate absorbs only small quantities of finishedproduct, thereby improving product yield.

[0022] Products prepared according to the described method have a purityof 93-95.5%, with an average of 95-95.5%, whereas prior methodologies attheir best have only reached a purity of about 93%.

[0023] The Gardner color units of the final product are decreased toabout 10 without the water wash or Magnesium acetate but with themagnesium silicate (as compared to about 15 without either treatment).The water wash or the magnesium acetate treatment plus the magnesiumsilicate treatment decreases the Gardner color units to about 1-2.

[0024] The features and advantages of the described method of the '262application as applied to the present invention will be more clearlyunderstood by reference to the following examples, which are not to beconstrued as limiting to the present invention.

EXAMPLES Example I

[0025] 1. trabromophthalic anhydride (464 grams), which typicallycontains 0.08-0.15% sulfuric acid, is dissolved in 2-ethylhexanol (390grams) at 90° C. as is known in the art.

[0026] 2. The solution is serially washed with aliquots of 300 grams ofhot water at 90C. until the residual sulfuric acid in the aqueous phaseis less than 0.1%.

[0027] 3. The solution is dried by azeotroping out water at 160-190° C.until the water content is less than 0.05%.

[0028] 4. The reaction mass is esterified at 195-205° C. in a 1 literreaction flask equipped with a Dean-Stark trap, with a catalyticquantity of tetra-2-ethylhexyl titanate (6 grams) until residual acidvalues are less than 0.5 meq/100 grams sample. The total esterificationtime is less than 6 hours.

[0029] 5. The excess 2-ethylhexanol is distilled off under vacuum,further reducing the residual acidity to less than 0.2 meq/100 gramssample.

[0030] 6. The reaction mass is cooled to 90° C. and treated with 7 gramsmagnesium silicate and 7 grams water, each of which is slurried into thereaction mass with mixing. The amount of water preferred is 1-2 timesthat of magnesium silicate (at 0.1 to 20 weight percent). The acid valueis checked before filtration (next step) to be sure that it is low.

[0031] 7. After treatment the reaction mass is dried under vacuum toless than 0.05% water and vacuum-filtered hot with a Buchner funnel asknown in the art. The resulting product (692 grams) has the followingproperties:

[0032] Appearance: Clear, slightly yellow liquid with no haze

[0033] Gardner Color: <1

[0034] Acidity: <0.001 meq/100 gram sample (ASTM D 1613-91)

[0035] GC Purity: 97.4%

[0036] Residual Titanium: <0.1 ppm (lower detection limit)

[0037] Residual Magnesium: <0.1 ppm (lower detection limit)

Example II

[0038] The serial water washing of Example I (step 2) is replaced withthe addition of 1.5 grams magnesium acetate. The resultant product isnearly colorless with equal product quality properties and yield as inExample 1.

Example III

[0039] The 2-ethylhexanol of Examples I or II is replaced with a mixtureof straight and branched chain alcohols (480 grams) with nine to elevencarbons (e.g., Neodol 91 manufactured by Shell Chemical Company). Theresultant product quality is comparable to the results of Examples I andII with a product yield of 750 grams. Product purity was slightly lowerdue to the mixed esters produced from the transesterification of thealkyl groups of the catalyst.

Example IV

[0040] The 2-ethylhexanol of Examples I or II is replaced with 432 gramsof 3,3,5-trimethyhexanol (also known as isononyl alcohol). The resultantproduct quality is comparable to the above examples with a product yieldof 719 grams. Product purity is slightly lower due to the mixed estersproduced from the transesterification of the alkyl groups of thecatalyst.

Example V

[0041] The 2-ethylhexanol of Examples I or II is replaced with a mixtureof straight and branched chain alcohols (516 grams) with eleven carbons(comparable to Neodol 1 manufactured by Shell Chemical or Lial 111manufactured by EniChem). The resultant product quality is comparable tothe above examples with a product yield of 774 grams. Product purity isslightly lower due to the mixed esters produced from thetransesterification of the alkyl groups of the catalyst.

Example VI

[0042] The 2-ethylhexanol of Examples I or II is replaced with aisodecyl alcohol (comparable to Exxal 10 manufactured by ExxonChemical)(474 grams). The resultant product quality is comparable to theabove examples with a product yield of 764 grams. Product purity isslightly lower due to the mixed esters produced from thetransesterification of the alkyl groups of the catalyst.

Example VII

[0043] The 2-ethylhexanol of Examples I or II is replaced withisotridecyl alcohol (comparable to Exxal 13 manufactured by ExxonChemical)(600 grams). The resultant product quality is comparable to theabove examples with a product yield of 828 grams. Product purity isslightly lower due to the mixed esters produced from thetransesterification of the alkyl groups of the catalyst.

Example VIII The 2-ethylhexanol of Examples I or II is replaced withn-octanol (comparable to Alfol 8 manufactured by Vista Chemical or Epal8 manufactured by Amoco)(390 grams). The resultant product quality iscomparable to the above examples with a product yield of 695 grams.Product purity is slightly lower due to the mixed esters produced fromthe transesterification of the alkyl groups of the catalyst.

[0044] From the above it can be seen how nearly colorless, highly pure,dialkyl tetrahalophthalates with an extremely low acid number wereprepared according to the '262 application. The description nextproceeds to describing how plasticized PVC compounds of the presentinvention are prepared.

[0045] II. PREPARATION OF PLASTICIZED PVC COMPOUNDS

[0046] In the present invention, dialkyl tetrachlorophthalate anddialkyl tetrabromophthalate are first individually prepared inaccordance with the above described method. Following which, inaccordance with the present invention, the dialkyltetrachlorophthalate-dialkyl tetrabromophthalate mixture can be preparedin any of a number of ways. For example, the two tetrahalophthalateproducts may be prepared separately and then mixed until a homogeneousone phase fluid is obtained. The two products may also be synthesizedsimultaneously. The mixtures can be prepared by synthesizing separatelyor together, by mixing the appropriate molar ratio oftetrachlorophthalic and tetrabromophthalic anhydrides with the C₁-₁₈alkanol in a reaction flask as described in detail above. As is wellknown in the arts, flame retardants must be in liquid form to plasticizePVC. See, Handbook of Polyvinyl Chloride Formulating, edited by EdwardJ. Wickson, 818-831, John Wiley & Sons (1993). The disclosure of thispublication and all other publications and patents referred to hereinare incorporated herein by reference.

[0047] The tetrahalophthalate mixture is then added and mixed with PVC,a flame retardancy synergist such as antimony trioxide, a plasticizersuch as trioctyl trimellitate, and a lead stabilizer which arecompounded into a flexible thermoplastic polymer, such as PVC for use onplenum wire and cable applications, where low-temperature flexibility isa desired PVC attribute. The dialkyl tetrahalophthalate mixtures cancomprise dialkyl tetrachlorophthalate to dialkyl tetrabromophthalate of1-99% to 99-1% by weight. However, the ratio of these two halophthalatesis preferably 1-50% dialkyl tetrachlorophthalate to dialkyltetrabromophthalate, but 25-33% dialkyl tetrachlorophthalate to dialkyltetrabromophthalate is most preferred.

EXAMPLES

[0048] For Examples A, B, and C below, composition components (base PVCpolymer, plasticizer, stabilizer, flame retardant synergist, and thedialkyl tetrahalophthalate mixture) were combined and thoroughly mixed.Initial mixing of the ingredients was done in a blender. The resultingcharge was transferred to a 2 roll mill and preheated to 350° F. forfusion and further mixing. Rolling time was for 5 minutes under 1260 psicompression at 337° F. for compression molding of the mixture into testsheets. The standard for PVC compression molding as known in the art isfully described in ASTM Designation: D-1928-90 and ASTM D-746. ASTMD-1928-90 and ASTM D-746 disclose the standard for preparing compressionmolded polyethylene test sheets and is also the standard for PVCcompression molding of the mixture into test specimens which, in thiscase, were subjected to physical, mechanical, and flame retardancytesting as described in Examples A, B, and C below.

[0049] Each Example includes tests to determine the tensile propertiesof the compressed PVC using standard dumbbell-shaped test specimens. Thestandard test method for testing tensile properties is found in the ASTMDesignation D-638, published in 1995. In summary, the test specimen isclamped by and between grips. The grips extend in opposed directionsthereby stretching the test specimens until the specimen breaks. Thetest specimens' tensile properties that were measured were: (1) TensileModulus, which is the ratio of stress to corresponding strain below theproportional limit of a material, expressed in force per unit area; (2)Tensile Strength at Break, which is the maximum tensile stress (tensileload per unit area of minimum original cross section) sustained by thespecimen during a tension test at specimen break; and (3) Elongation,which is the elongation of a test specimen expressed as a percent of thegage length. An increase in these test factors indicates a more flexibletest specimen

[0050] Test specimen hardness was also measured. The standard hardnesstest method is found in the ASTM D-2240, published in 1995. In summary,the test method results are based on the penetration of a indentor whenforced into the test specimen.

[0051] Flame retardancy of the control and test formulations weredetermined by the Designation ASTM D-2863, published in 1995, to giveoxygen index values. The oxygen index is equal to the minimumconcentration of oxygen, expressed as volume percent, in a mixture ofoxygen and nitrogen that will just support flaming combustion of amaterial initially at room temperature. An higher oxygen index indicateshigher flame retardancy.

[0052] The test specimens were tested for the density of smoke generatedby burning the test specimens in an NBS Smoke Chamber using the flamingmode in accordance with the ASTM E662-95 publication.

[0053] The test specimens were also tested for Brittleness Temperature.Brittleness temperature is the temperature at which 50% for thespecimens probably would fail. The brittleness of a test specimen isdetermined by immersing the specimen in a bath containing a heattransfer medium that is cooled. The specimens are struck at strikingelement at specified linear speed and then examined. The brittlenesstemperature is the temperature at which 50% of the specimens fail.

Example A

[0054] PVC resin (the base PVC resin used was GEON 30, a product of theGEON COMPANY) was compounded in a 2 roll mill in accordance with theprocedures disclosed in ASTM D-1928 using the below mentioned Controland Test Formulations. The quantities of components are indicated inparts by weight per hundred parts by weight resin. Formulations CONTROLFORMULATION Parts per Hundred TEST FORMULATION Resin Parts per HundredResin COMPONENT (PHR) (PHR) PVC Resin (Geon 30) 100 100 AntimonyTrioxide 15 15 Trioctyl Trimellitate 34.3 34.3 (UNIPLEX ™ 546-A) LeadStabilizer 5 5 Dioctyl 40 30 Tetrabromophthalate (UNIPLEX ™ FRP-45)Dioctyl 0 10 Tetractlorophthalate (UNIPLEX ™ FRP-27) CONTROL TEST TESTPROCEDURE FORMULATION FORMULATION Tensile Modulus at 100% 1760 1963Strain (psi) (ASTM D638-95) Tensile Strength at Break 2050 3391 (ASTMD638-95) Elongation (%) 278 370 (ASTM D638-95) Shore A Hardness 88 94(ASTM D-224095, A Scale) Oxygen Index 33 37 (ASTM D2863-95) NBS Smoke440 276 (ASTM E662-95) Flam- ing (Dmc) Non-flaming (Dmc) 180 140

Example B

[0055] Dialkyl tetrabromophthalates were prepared from the reaction ofLINEVOL™ 91 alcohol (produced by SHELL CHEMICAL, CAS Registry Number is68603-15-6) with tetrabromophthalic anhydride to produce adi(nonyl/decyl/undecyl) tetrabromophthalate mixture in accordance withthe preferred method of producing dialkyl tetrahalophthalates describedabove. LINEVOL™ 911 is a mixture of nonyl(C₉), decyl (C₁₀), and undecyl(C₁₁) alcohols with 75-85% by weight normal alcohols and the remainderbeing 2-n-alkylisomers, principally 2-methyl. Since tetrahalophthalateanhydride has two reactive acid functions; dialkyl tetrahalophthalatesare produced as illustrated immediately below:

[0056] Where R=C₉ or C₁₀ or C_(11.)

[0057] Where R′=C₉ or C₁₀ or C_(11.)

[0058] Where X=halogen.

[0059] Therefore, there are seven different diesters possible where thealkanol carbon chain lengths are:

[0060] di C₉, C₉C₁₀, C₉C₁₁

[0061] di C₁₀, C₁₀C₁₁

[0062] di C₁₁, C₁₁, C₉

[0063] In this case, the resultant brominated diesters were mixed withthe dioctyl tetrachlorophthalate, preferably prepared in accordance withthe method for producing dialkyl tetrahalophthalates described above, atroom temperature until a homogeneous one phase liquid mixture wasproduced. The tetrahalophthalate mixture was then compounded into PVC aspreviously described and as is well known in the art. Formulations:CONTROL TEST FORMU- FORMULATION LATION Parts Parts per Hundred Resin perHundred Resi COMPONENT (PHR) (PHR) PVC Resin (Geon 30) 100 100 AntimonyTrioxide 15 15 Trioctyl Trimellitate 34.3 34.3 (UNIPLEX ™ 546-A) LeadStabilizer 5 5 Di(nonyl/decyl/undecyl) 40 30 Tetrabromophthalate Dioctyl0 10 Tetractlorophthalate (UNIPLEX ™ FRP-27)

[0064] UNIPLEX is a trade name for the named compound owned by UnitexChemical Corporation. CONTROL TEST TEST PROCEDURE FORMULATIONFORMULATION Tensile Modulus at 100% 1800 1960 Strain (psi) (ASTMD638-95) Tensile Strength at Break 2010 3410 (ASTM D638-95) Elongation(%) 284 385 (ASTM D638-95) Shore A Hardness 88 94 (ASTM D-224095, AScale) Oxygen Index 33 37 (ASTM D2863-95) NBS Smoke 460 284 (ASTME662-95) Flaming (Dmc) Non-flaming (Dmc) 200 140 Brittleness Temperature−21 −34 Testing, ° C., (ASTM D746-95)

Example C

[0065] PVC resin (Geon 30 from the Geon Company was compounded in a 2roll mill by ASTM D 746 using the below mentioned formulations. PARTSPER HUNDRED PARTS PER RESIN HUNDRED RESIN COMPONENT (PHR) (PHR) PVCResin (Geon 30) 100 100 Antimony Trioxide 15 15 Trioctyl Trimellitate34.3 34.3 (Uniplex 546-A) Lead Stabilizer 5 5 Dioctyl 20 10Tetrabromophthalate (Uniplex FRP-45) Dioctyl 20 30 Tetractlorophthalate(Uniplex FRP-27)

[0066] The resultant resin was compression molded into test specimensand subject to physical, mechanical, and flame retardancy testing. Theresults are shown in the table below: PARTS PER PARTS PER HUNDREDHUNDRED RESIN TEST PROCEDURE RESIN (PHR) (PHR) Tensile Modulus at 100%2050 2180 Strain (psi) (ASTM D638- 95) Tensile Strength at Break 34503560 (ASTM D638-95) Elongation (%) (ASTM 385 390 D638-95) Shore AHardness (ASTM 94 94 D-224095, A Scale) Oxygen Index (ASTM 41 44D2863-95) NBS Smoke (ASTM 270 220 E662-95) Flaming (Dmc) Non-flaming(Dmc) 130 110 Brittleness Temperature −28 −32 Testing, ° C., (ASTM −28−32 D746-95)

[0067] As illustrated by the Examples A, B, and C for the preparation ofthe plasticized PVC of the present invention, PVC mixtures oftetrabromophthalates and tetrachlorophthalates can be used to formhighly flame retardant plasticized PVC with improved low temperatureflexibility. As a related discovery, it has also been found that PVC ofthe present invention also result in less than normal smoke generationwhen ignited.

[0068] While the invention has been described with reference to specificembodiments thereof, it will be appreciated that numerous variations,modifications, and embodiments are possible, and accordingly, all suchvariations, modifications, and embodiments are to be regarded as beingwithin the spirit and scope of the invention.

What is claimed is:
 1. A flame retarded plasticized flexible compositioncomprising: a. a polyvinyl chloride resin; b. a flame retardantsynergist; C. a stabilizer; and d. a mixture comprising: i.tetrachlorophthalate; and ii. tetrabromophthalate; in amounts whichincrease the flexibility of said flame retarded composition at lowtemperatures.
 2. A flame retarded plasticized flexible composition asrecited in claim 1 , wherein in said mixture said tetrachlorophthalateis incorporated with said tetrabromophthalate in the ratio of 1-99% to99-1% by weight.
 3. A flame retardant plasticized flexible compositionas recited in claim 1 , wherein said tetrachlorophthalate isincorporated with said tetrabromophthalate in the ratio of 1-50% byweight.
 4. A flame retarded plasticized flexible composition as recitedin claim 1 , wherein a said tetrachlorophthalate is incorporated withtetrabromophthalate in the ratio of 25-33% by weight.
 5. A flameretarded plasticized flexible composition as recited in claim 1 ,wherein said tetrachlorophthalate and said tetrabromophthalate are eachprepared in accordance with the process, comprising: a. dissolving atetrahalophthalic compound selected from the group consistin oftetrahalophthalic anhydrides and tetrahalophthalic acids, in a C₁-C₁₈alkanol, to form a reaction mass; b. removing residual sulfuric acidfrom the reaction mass using a treatment selected from the groupconsisting of serial water washes, and treatment with a first Group IIalkali metal salt of a low number carbon chain organic acid; C. removingwater from said reaction mass; d. esterifying with an alkyl titanatecatalyst; and e. treating with a second Group II alkali metal salt andwater to decolorize and remove residual metal contamination and acidity.6. A product formed of: a. a polyvinyl chloride resin; b. a flameretardant synergist; c. a stabilizer; and d. a mixture comprising: i.tetrachlorophthalate; and ii. tetrabromophthalate; in amounts whichincrease the flexibility of said flame retarded composition at lowtemperatures.
 7. A product as claimed 6, wherein said product compriseselectrical insulation.
 8. A product as claimed in claim 6 wherein saidproduct comprises a coating.
 9. A product as claimed in claim 6 whereinsaid product comprises a jacket.
 10. A product as claimed in claim 6wherein said product comprises a sheet.